Non-LED backlights often require higher voltages I. Mode selection[ edit ] Selecting 4-bit or 8-bit mode requires careful selection of commands. There are two primary considerations. First, with D3-D0 unconnected, these lines will always appear low 0b to the HD when it is in 8-bit mode.
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Power Banks The exact component used for this tutorial can be bought via the links attached and the power bank is only required to run the Arduino when not connected to the computer. You can replace this with a 9V battery and a center-positive power jack.
Schematics Since the display and the real-time clock are both I2C devices, they will be connected to the same pins on the Arduino. This may differ on any of the other Arduino boards. Connect the components as shown in the schematics below; Schematics To make the connections, even more easier to follow, the pin connections of the components is described below.
While the Wire library comes built into the Arduino IDE, the other two libraries can be downloaded and installed via the links attached to them. As mentioned during the introduction, our task for today is to obtain time and date information from the RTC module and display on the LCD.
As usual, I will do a breakdown of the code and try to explain some of the concepts within it that may be difficult to understand. We start the code by including the libraries that will be used. The custom characters are usually 5pixels in width and 8 pixels in height, representing each box in the rows or columns of the LCD. The byte array represents which pixels of the box to be turned on or off. After this, the CreateCustomCharacters function is called to convert the char variables created above into characters that can be displayed on the LCD.
The idea behind the voidloop function is simple. This is all done within an if statement which prints the time and date value stored in tm, if a response is received from the rtc. If a response is not received, the else statement is executed. These values are then displayed on the LCD using the lcd. Hour ; lcd. Minute ; lcd. Second ; lcd. It extracts date information from the variable tm and uses the lcd. Month ; lcd. Day ; lcd. The createCustomCharacters function, as the name implies, is used to create custom characters using byte arrays.
The function takes two arguments; the character number, and the variable to in which the byte array for that character is stored. Only 7 characters can be created at once as such the character number is usually between 1 and 7.
Each of the custom characters created is displayed using the lcd. The characters are positioned on the LCD using the lcd. Ensure all the libraries have been installed to avoid errors. With the upload done, you should see the time and date is displayed on the LCD as shown in the image below. Demo Different projects, come with different screen requirements. Feel free to reach me via the comment section with any question about the project.
The video version of this tutorial is available on youtube.
Hitachi HD44780 LCD controller
Using a 20×4 I2C Character LCD display with Arduino Uno